Spam’s Noxious Carbon Footprint

Email users may already hate spam, but perhaps they’ll be gratified to know that it’s also bad for the environment.

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Calculating one’s carbon footprint may be all the rage, but in the case of spam, it’s serious, according to a study released Wednesday by computer security company McAfee Avert Labs. The report found that an estimated 62 trillion spam messages are sent each year. Each email is associated 0.3 grams of carbon dioxide released as greenhouse gas, the equivalent of driving three feet — but given the total volume of spam each year, it’s like driving around the earth 1.6 million times.

The study, which was conducted by consulting firm ICF International, concluded that spam-related emissions for all email users world-wide creates a total of 17 million metric tons of carbon dioxide per year, 0.2% of total greenhouse gas emissions.

Legitimate emails release four grams of CO2 compared with spam’s 0.3 grams, but since spam accounts for one-third of all business and personal messages, it adds up, says Dave Marcus, director of security research and communications for McAfee Avert Labs. “At this point in time, everyone has an email address,” he says. “I think it should resonate with a lot of people. The more we can keep [spam] away from users, the better the planet ends up.”

The process of creating and dealing with spam involves a number of different energy-using steps, the report explains, from harvesting addresses to managing spam messages in one’s inbox. But almost 80% of the greenhouse gases created by spam actually comes from the process of deleting it, or by searching around for legitimate emails trapped in spam filters.

So what can consumers do? Mr. Marcus says they should be careful about how they search the Internet and where they leave their email addresses, which will prevent them from being picked up by malware and will result in less spam in their inboxes from the start. But they should also use spam-filtering technology and make sure their email providers have installed the proper filters. The report found that spam filtering saves 135 terrawatt hours of electricity a year, the equivalent of taking 13 million cars off the road.

“It’s not rocket science,” Mr. Marcus says. “Most people [receive] an average of 45 spam messages per day. Do the math over the year, and the environment’s just better off.”